Ostomy appliances of so-called one-piece and two-piece constructins are commonly provided with adhesive faceplates for adhesively securing the appliances to the peristomal skin surfaces of wearers. While medical grade pressure-sensitive adhesives, usually acrylic adhesives, have been used in the past, recent products have utilized moisture-absorbing, hydrocolloid-containing skin barrier materials for adhesive attachment of faceplates. Such materials are considered "skinfriendly" because they are generally non-allergenic, absorb moisture from the skin and, following a normal interval of use, are of sufficiently reduced tackiness that may be easily peeled away without damaging or irritating the skin.
One skinfriendly adhesive barrier material is disclosed in U.S. Pat. No. 3,339,546 and consists of a blend of a water-soluble and swellable hydrocolloids such as polyvinyl alcohol, powdered pectin, gelatin or carboxymethylcellulose, and a water-insoluble viscous gum-like elastic binder such as natural rubber, silicone rubber, polyurethane rubber, or (notably) polyisobutylene. Tackifiers and plasticizers may be included to vary the properties of such compositions.
In such hydrocolloid-containing barrier compositions, the elastomer constitutes a continuous phase and the hydrocolloid or hydrocolloids are dispersed therein in particulate form. As the hydrocolloids absorb moisture, such a composition swells and begins to lose its integrity. Steps may be taken to retard or prevent barrier disintegration or dissolution, such as by incorporating a polymer capable of being cross-linked by irradiation (see U.S. Pat. Nos. 4,477,325 and 4,738,257). Other barrier compositions that resist disintegration/dissolution have been formulated in which the continuous phase includes a physically cross-linked elastomer consisting of one or more styrene-olefin-styrene block copolymers, a hydrocarbon tackifier resin, and an antioxidant, and a disperse phase consisting of one or more water-swellable hydrocolloids (see U.S. Pat. No. 4,867,748).
One aspect of this invention lies in the observation that the properties which make a barrier material skinfriendly for use in an ostomy appliance, such as ease of removability without skin damage following an interval of use, tend to be compromised to a greater or lesser extent when the composition is formulated to resist dissolution or disintegration upon hydration. On the other hand, it is important that the barrier material of an ostomy appliance function as an effective sealant to prevent leakage of stomal fluids and to protect the peristomal skin surfaces from the aggressive action of such enzyme-containing fluids.
The present invention addresses these problems by providing an ostomy appliance in which the faceplate assembly includes two layers of hydrocolloid-containing adhesive barrier materials of different compositions. The first or primary layer secures the faceplate to the peristomal skin surfaces and is composed of a skinfriendly hydrocolloid-containing barrier material that has relatively low resistance to dissolving and/or disintegrating when contacted by stomal fluids. The second layer directly surrounds the stomal opening of the faceplate and is composed of a relatively soft, easily-deformable and extrudable, adhesive sealant material that is more resistant to dissolution or disintegration by stomal fluids than the material of the first layer. The soft, moldable sealant material may therefore be extruded or displaced inwardly and axially by finger pressure, following initial attachment of a faceplate by means by the first skinfriendly hydrocolloid layer, to form a stoma-contacting gasket that prevents stomal fluids from attacking the peristomal skin surfaces and from reaching and/or dissolving/disintegrating the primary adhesive layer.
Such an arrangement and its use also tends to protect the stoma against direct contact with the inner edges of the patch material (preferably a microporous non-woven material) of the faceplate about its stoma-receiving opening, as well as the edges that define the stoma-receiving opening of the pouch.
Other features, objects, and advantages of the invention will become apparent from the description and drawings.